1. Field of the Invention
The present invention relates to multilayer capacitors each including a capacitor body and a plurality of outer connectors provided on outer surfaces of the capacitor body, wherein the capacitor body includes a plurality of dielectric layers and a plurality of conductor layers stacked alternatingly.
2. Description of the Related Art
Generally, as a multilayer capacitor, a multilayer ceramic capacitor includes a capacitor body formed by stacking alternatingly a plurality of dielectric layers composed of a ceramic material and a plurality of conductor layers composed of an electrically conductive material. The multilayer ceramic capacitor is configured so as to have electrostatic capacitance provided by these stacked plurality of dielectric layers and plurality of conductor layers.
In recent years, with advancements in performance of electronic devices, higher capacitance multilayer ceramic capacitors are being developed. In high capacitance multilayer ceramic capacitors, ceramic materials having high dielectric constants such as barium titanate (BaTiO3) and the like are used as the dielectric material.
These high dielectric constant ceramic materials have piezoelectricity and an electrostrictive property. Thus, in the multilayer ceramic capacitor including dielectric layers composed of the high dielectric constant ceramic material, a mechanical distortion occurs when voltage is applied.
Therefore, when an alternating-current voltage, a direct-current voltage on which an alternating-current component is superposed, or the like is applied to a high capacitance multilayer ceramic capacitor mounted on a wiring board, vibration occurs due to the mechanical distortion occurring in the ceramic material. When this vibration propagates to the wiring board, a circuit board vibrates.
Here, in a case where the propagated vibration causes the circuit board to vibrate at a frequency within the range from about 20 Hz and about 20 KHz that is an audible frequency range, audible noise occurs. This audible noise is what is called squeaking (acoustic noise). This kind of audible noise is problematic in various electronic devices such as television receivers, personal computers, mobile communication terminals such as typified by cellular phones and smartphones, and the like, which include multilayer ceramic capacitors as electronic components.
To suppress occurrence of such audible noise, for example, Japanese Unexamined Patent Application Publication No. 2010-45085 proposes an arrangement of four elongated substantially cuboid multilayer ceramic capacitors, which are mounted on a wiring board, in accordance with a predetermined layout rule in such a way that vibrations propagating from the respective multilayer ceramic capacitors are partially cancelled on the wiring board.
However, in the case where an arrangement such as disclosed in the Japanese Unexamined Patent Application Publication No. 2010-45085 is adopted, the number of the multilayer ceramic capacitors always needs to be the integral multiple of four, and furthermore, these multilayer ceramic capacitors need to be arranged in accordance with the predetermined layout rule. These greatly reduce flexibility in circuit board designing and pose a problem. Particularly, in the mobile communication terminals and the like, such as typified by cellular phones and smartphones, there is strong demand of high-density packaging of electronic components. In some cases, it is difficult to adopt an arrangement such as disclosed in the Japanese Unexamined Patent Application Publication No. 2010-45085.